1. Field of the Invention
Embodiments of the invention generally relate to an integrated processing system configured to process semiconductor substrates. More particularly, the invention relates a cluster tool has a mainframe including a transfer chamber and an extension chamber configured to store shutter disks therein.
2. Description of the Related Art
The process of forming semiconductor devices is commonly done in a multi-chamber processing system (e.g., a cluster tool) which has the capability to process substrates, (e.g., semiconductor wafers) in a controlled processing environment. A typical controlled processing environment includes a system that has a mainframe which houses a substrate transfer robot configured to transport substrates among a load lock chamber and multiple vacuum processing chambers, which are connected to the mainframe. The controlled processing environment has many benefits, such as minimizing contamination of the substrate surfaces during transfer and during completion of the various substrate processing steps. Processing in a controlled environment thus reduces the number of generated defects and improves device yield.
A mainframe for a cluster tool generally includes a central transfer chamber housing a robot adapted to shuttle one or more substrates. Processing chambers and load locks are mounted on the central transfer chamber. During processing, an internal volume of the central transfer chamber is typically maintained at a vacuum condition to provide an intermediate region in which substrates may be shuttled from one processing chamber to another, and/or to a load lock chamber positioned at a front end of the cluster tool.
Some processing chambers, such as a physical vapor deposition (PVD) chamber, comprise a shutter disk which may be used to protect a substrate support during conditioning operation. Typically, a PVD processing is performed in a sealed chamber having a pedestal for supporting a substrate disposed thereon. The pedestal typically includes a substrate support that has electrodes disposed therein to electrostatically hold the substrate against the substrate support during processing. A target, generally comprised of a material to be deposited on the substrate, is supported above the substrate, typically fastened to a top of the chamber. A plasma formed from a gas, such as argon, is supplied between the substrate and the target. The target is biased, causing ions within the plasma to be accelerated toward the target. Ions impacting the target cause material to become dislodged from the target. The dislodged material is attracted towards the substrate and deposit a film of material thereon.
Conditioning operations, such as burn-in process, pasting, and/or cleaning operations, are performed periodically to ensure processing performance of the PVD chamber. During conditioning operations, a dummy substrate or a shutter disk is disposed on the pedestal to protect the substrate support from any deposition or particle contamination. The state of the art PVD chambers generally include a shutter disk storage space designated storing a shutter disk during process, and a robotic arm configured to transfer the shutter disk between the shutter disk storage space and the substrate support for conditioning operations. The shutter disk stays in the shutter disk storage space within the PVD chamber during deposition, and covers the substrate support during conditioning operations. The shutter disk storage space and the robotic arm designed to transfer the shutter disk increases complexity and volume of the PVD chamber.
FIG. 1A schematically illustrates a PVD processing chamber 10 of prior art. The PVD processing chamber 10 includes a chamber body 2 and a lid assembly 6 that defines an evacuable process volume. The chamber body 2 generally includes sidewalls and a bottom 54. The sidewalls generally contain a plurality of apertures that include an access port, pumping port and a shutter disk port 56 (access and pumping ports not shown). The sealable access port provides for entrance and egress of the substrate 12 from the PVD processing chamber 10. The pumping port is coupled to a pumping system (also not shown) that evacuates and controls the pressure within the process volume. The shutter disk port 56 is configured to allow at least a portion of a shutter disk 14 therethrough when the shutter disk 14 is in the cleared position. A housing 16 generally covers the shutter disk port 56 to maintain the integrity of the vacuum within the process volume.
The lid assembly 6 of the body 2 generally supports an annular shield 62 suspended therefrom that supports a shadow ring 58. The shadow ring 58 is generally configured to confine deposition to a portion of the substrate 12 exposed through the center of the shadow ring 58.
The lid assembly 6 further includes a target 64 and a magnetron 66. The target 64 provides material that is deposited on the substrate 12 during the PVD process while the magnetron 66 enhances uniform consumption of the target material during processing. The target 64 and substrate support 4 are biased relative each other by a power source 84. A gas such as argon is supplied to the process volume 60 from a gas source 82. A plasma is formed between the substrate 12 and the target 64 from the gas. Ions within the plasma are accelerated toward the target 64 and cause material to become dislodged from the target 64. The dislodged target material is attracted towards the substrate 12 and deposits a film of material thereon.
The substrate support 4 is generally disposed on the bottom 54 of the chamber body 2 and supports the substrate 12 during processing. A shutter disk mechanism 8 is generally disposed proximate the substrate support 4. The shutter disk mechanism 8 generally includes a blade 18 that supports the shutter disk 14 and an actuator 26 coupled to the blade 18 by a shaft 20. Typically, the blade 18 is moved between the cleared position shown in FIG. 1A and a second position that places the shutter disk 114 substantially concentric with the substrate support 4. In the second position, the shutter disk 14 may be transferred (by utilizing the lift pins) to the substrate support 4 during the target burn-in and chamber pasting process. Typically, the blade 18 is returned to the cleared position during the target burn-in and chamber pasting process. The actuator 26 may be any device that may be adapted to rotate the shaft 20 through an angle that moves the blade 18 between the cleared and second positions.
FIG. 1B schematically top and sectional plan views of the PVD processing chamber. FIG. 1B illustrates the housing 16 relative to the shutter disk 14, the blade 18 and the substrate support 4.
Therefore, the state of the art PVD processing chambers with built-in shutter disk storage and transfer mechanism are not only complex but also bulky. There are usually multiple processing chambers require a shutter disk in a cluster tool configured to perform one or more PVD process steps. With multiple chambers having shutter disk storage and transferring mechanisms, footprint and cost of a cluster tool can be increased greatly.
Therefore, there is need for an efficient shutter disk storage and transferring mechanism in a cluster tool.